Pulsed radio remote-control system



July 14, 1953 E. L ABIN PULsED RADIO REMOTE-CONTROL SYSTEM Filed April 18, 1945 Patented July 14, 1953 PULSED- RADIO Emile Labin, New York, N. Y., as si'gnor l'edleral Telephone and. Radio Corporation, New York,

N'. Y., a corporation of'Delawa're "f Application April 18, 1945,y Serial No. 588,961

s'olaims. (o1. 34a-.225): 4., 'f

The present invention relates to remote c011- trol systems and particularly to ar radio remote control system for the selective control of a plurality of separate utilization devices.

For certain uses, particularly military, it is desirable toV have a remote control radio system which is not easily detected and which cannot be readily jammed or affected by noises. Furthermore if such systems are to be used for the control of moving craft or vehicles, as for example the control-vof a pilotless glider from a mother plane, it is desirable that the control equipment be relatively simpleV in construction and operation, positive in action, and capable of operating on rather small power systems. q

An object of the present invention is the provision of a remotecontrol radio system which will meet the foregoing requirements:

In carrying out my invention, control is effected by energy ofV a given carrier frequency in the form of pulses of preferably several hundred microseconds duration. The use of pulses permits obtaining relatively large amounts of power for short periods of time from relatively small power equipment. Furthermore, since, Vaccording to my invention, these pulses are transmitted only when changes are to be made in the operation of the control device, as for example changes in the direction of the pilotless glider,

these pulses are not readily detected. Since these pulses are not continuously transmitted in order for them to be detected, the receiver must be tuned to the proper wavelength at the proper time.

To effect different controls such as up and down, right and left, required .in controlling the movements of the glider, for example, the carrier frequency of the transmitted pulses (from the controlling plane) is modulated byaselected one of a number of sub-carrier frequencies. In the receiver (in the pilotless glider) the pulses are separated according to the sub-carrier frequency with which they are modulatedl and sent along a given channel to actuate a utilization device which produces the desired operation (change in direction of the glider).

Other and further objects of the present invention will become apparent an-d my invention will be best understood from the following descriptionY of an embodiment thereof, reference being had to the drawing, in which:

Figurel is a block diagram of a remote contro system embodying my invention; and

Figure 2 is. a plan view of the Qontrol box 4 with the ooverremoved,

Since the particular embodiment of my invention illustrated inthe F'ig.I 1 is adapted to control the flightbf a glider from a mother plane, it willbe described inY connection therewith. The system consists. of 'a transmitter I which is mounted Yin the-planeand a receiver 2 which is mounted.' in the glider..A Flight of the glider is controlled from .the plane by moving an arm 3. in a control box 4 to .various positions designated, such .asfor'example left, right, up, down and reset to A'actuate 'relays 5.,-9 in the receiver which relays con-trol the flight of the glider by controlling the rudder. elevators, ailerons, etc. The control box tisgprovided with switches or relays arranged so vthatwhen the arm 3 is moved into any of thefoperativepositions (left, right, up, down andresetl two operations occur.

The first of these .operations is the actuation of the pulse generator rIii, Vthe pulse output of which is passed through an amplifier I I and then used to key.asub-carriervfrequency oscillator I2. The pulses keying oscillator I2 are preferably relatively long such asv for example of the order of 200 microseconds. f

The secondof theoperations is to select a sub-carrirerfrequency. Oscillator I2 operates at one of the five sub-carrier frequencies, preferably spaced over a bandwidth 'of the order of one megacyclethe five lfrequencies ranging for example from one to two or two to three mega,- cycles or the like..4' The ,particular frequency at which oscillator I2 operates for a given pulse or train of pulsesis-determined bythe operative position to which 'arm 3 of ycontrol box I is moved. For this purpose control box Il is connected by lines I3-Il, .one line yfor each operative position of arm 3, to oscillatorIZ and through these lines the control box Il, controls or determines the particular frequency at which oscillator I2 operates. lhiswmayA be;.acc0mplished by any well-known meansy Ysuch as for example by con-A necting said linesinside ,the .oscillator to elec.- tronic switches.whichT switch .different tank coils into the oscillator platev circuit.

V'The output ofoscillator I2 is in the form of pulses carrying-the selected one of the subcarrier fre'luencyoscillations` This energy is used tov modulatea carrier frequency oscillator I8, as lfor example byplate modulation. The carrier frequency oscillator I8 is also keyed by the pulses from amplifier. II as indicated by line rier frequency modulated with the selected subcarrier frequency.l The output of oscillator I8 is next fed to a broad band antenna system 20 and thereby radiated.

The receiver 2 in the glider picks up this energy on its antenna system 2|, the pulse then being fedthrough a broad band Kradio frequency amplier 22 tuned to the carrierv frequency, to a `detector 23 in which the carrier frequency is removed. The output of detector 23 is fed through a high pass filter 24, which reduces the effects of harmonics in the sub-carrier frequencies, to an amplifier 25 preferably of the type known as video ampliers and giving a relatively' flat respense over the entire sub-carrier frequencyband separate channels designated generally by ,the 1 numerals 26-39. Since all of these channels are similar in construction, only channel 26 will be described. The output of amplifier 25 is connected to a selector filter 3| in channel 26 which is designed to pass one of Ythe five sub-carrier frequencies. The other channels have similar selectorliilters, each of which passes a vdilferent one of the ve sub-carrier frequencies. The output of lter 3i is fed to a limiter 32 of the threshold clipping type. This limiter serves to prevent pulses of less than a given amplitude from controlling the operation of theglider. This also serves to prevent interference with said operation by noise or jamming. The output of limiter 32 is then fed vthrough anintegrator 33 in which the train of pulses is integrated and thence to a sensitive relay 5, which relay controls one of the movements of the glider in flight, as for example either up, down, right, left orv reset. Likewise each ofrelays 6, 1, 8 and Srconnected in channels 27-29 respectivelyA controls a diiferent movement of the glider. K n

` While numerous control boxes suitable for controlling the transmitter, as indicated hereinabove, may be employed and would readily occur to those versed in the art, a simple one for this purpose is illustrated in Fig. 2. Referring now to said figure, the control box 4 there illustrated includes switches 34, 35, 36, 31 and 38 adapted to control operation to the other glider asl'follows, right, up, left, down, and reset, respectively. Movement of arm 3 into any one of four given positions will operate one of the switches 313-31, and change the direction of flight of the glider and movement of arm 3 back to the central position will operate reset switch 38 and cause the glider to fly in 'a straight direction. Since it is desired that pulses should onlybe sent out when operative controlis to be had of the glider there are positions of the arm 3 intermediate its central position, where it actuates reset switch 33, and the position in which it actuates one of the other switches 34-3`L Where none of the switches are actuated and no signal is transmitted.

While I have described one simple control box, it will be apparent that numerous types of control boxes may be provided which will function in the manner hereinabove indicated.

It will be seen that the aforedescribed system has numerous safeguards against detection and interference. Transmission is in the form of separate pulses or discrete series of pulses. These pulses are modulated with two distinct frequencies, both of which must be determined in order to interfere with the receiver. The interference must have a relatively high amplitude because of the operation of the threshold device 0r lmiter 32, which prevents pulses of lesser amplitude Y from affecting the relays. Furthermore, the system permits of numerous changes to be made in order to prevent anyone from learning the combinations involved. The carrier frequency can be readily changed. Because of the width of the `sub-carrier frequency bandgany .of the ve subcarrier frequencies can bev shiftedfoverj-a relative1y wideband. Likewise die 'sub-'carrier rre not' as'a'limitation on the scope of my invention.

I claim: 1. In a'remote control radio system, a trans-- mitter comprising a single energy pulse generator, a first' oscillator keyed by said pulse generator and adapted to generate oscillations at a selected one of `a plurality of sub-carrier frequencies, a second oscillator keyed by said pulse generator and modulated by said first oscillatorand adapted 'to generate carrier frequency oscillations, control means 'for substantially simultaneously actuating said pulse generator and selecting the sub-frequency of said rst oscillator, and transmitter means for transmitting the outputY of said second oscillator; and a receiver' comprising means for receiving andselecting pulses of said given carrier frequency anddetecting them to remove the carrier'frequency, meansv for directing said pulses to one of a numberof channels inV accordance with the pulse sub-carrier frequency, threshold means in said channels for blocking all energy having less than a given amplitude, and devices arranged'in said channels adapted tobe actuated by said pulses. 2. In a transmitter having a main carrier cscillator; oscillator means for producing any one of a plurality of predetermined sub-frequency signals as modulating energy for said main carrier oscillator, a single energy generator for simultaneouslykeying said main carrier oscillator and said oscillator means, and control'means for said single energy generator and said oscillator means for selectivelydetermining the sub-frequency output of said oscillator means during the operationy of said single energy generator. l3. A transmitter' comprising a single energy pulse'generator, a rst oscillator keyed by pulses from said generator and adapted to generate oscillations at al selected one of a plurality of sub-carrier frequencies, a second oscillator keyed by said single energy generator and modulated by said first oscillator and adapted to generate carrier frequency oscillations, controlmeans for substantially simultaneously actuating said single energy generator and selecting the sub-frequency of said first oscillator, and means for transmitting the output of said second oscillator.

4. In a remote-control radio system, a transmittercomprising a source of carrier frequency,

means for selectively generating a plurality of sub-carrier frequencies, means coupled'to said source and saidA selective generating means for generating pulses to control operation of said source and said Vselective generating means, control means forcontrolling operation of said pulse generating means and for selecting a particular one of said 'sub-carrier frequencies, means for modulating energy from said source with said selected sub-carrier frequency; and a receiver comprising means for receiving and selecting pulses of said given carrier frequency, means for detecting said last mentioned. pulses to remove the carrier frequency, means for directing said pulses to one of a number of channels selected in accordance with the pulse sub-carrier frequency, and devices arranged in each of said channels adapted to be actuated by said pulses.

5. A transmitter comprising a source of carrier frequency, means for selectively generating a plurality of sub-carrier frequencies, means coupled to said source and said selective generating means for generating pulses to control operation of said source and said selective generating means, control means for controlling operation of said pulse generating means and for selecting a particular one of said sub-carrier frequencies, and means for modulating energy from said source With said selected sub-carrier frequency.

6. A radio remote-control system comprising a source of carrier frequency, means for selectively generating a plurality of sub-carrier frequencies, means coupled to said source and said selective generating means for generating pulses to control operation of said source and said selective generating means, control means for controlling operation of said pulse generating means and for selecting a particular one of said subcarrier frequencies, means for modulating energy from said source With said selected subcarrier frequency, means for receiving said modulated carrier frequency a plurality of translating means coupled to said receiving means, each adapted to respond in accordance with the selected sub-carrier frequency.

EMILE LABIN.

Number Name Date 1,566,245 Brackett Dec. 15, 1925 1,597,416 Mirick Aug. 24, 1926 1,737,671 O-hl Dec. 3, 19,29 1,802,745 Whitaker Apr. 28, 1931 1,870,795 Davis Aug. 9, 1932 1,887,237 Finch Nov. 8, 1932 1,898,477 Bohm Feb, 21, 1933 2,165,800 Koch July 11, 1939 2,178,089 Walker Oct. 31, 1939 2,205,469 Curtis June 25, 1940 2,245,347 Koch June 10, 1941 2,264,510 Cox Dec. 2, 1941 2,282,102 Tuniek May 5, 1942 2,325,829 BosWau Aug. 3, 1943 2,328,944 Beatty Sept. 7, 1943 2,361,437 Trevor Oct. 31, 1944 2,368,778 Purington Feb.6, 1945 2,369,662 Deloraine Feb. 20, 1945 2,388,748 Kopetzky Nov. 13, 1945 2,397,088 Clay Mar. 26, 1946 2,397,475 Dinga Apr. 2, 1946 2,413,621 Hammond, Jr Dec. 31, 1946 FOREIGN PATENTS Number Country Date 509,866 Great Britain July 24, 1939 

